Golf club head with increased shaft bonding strength

ABSTRACT

Embodiments of a golf club comprising a club head, a shaft, and features that improve bonding strength between the club head and the shaft are described herein. The club head comprises a hosel that receives a tip end of the shaft. The shaft tip end defines a shaft bonding area and an effective bonding area. The features described herein are designed to increase the effective shaft bonding area with the hosel to improve bonding strength between the club head and the shaft. In some embodiments, the features comprise microgrooves located within the shaft bonding area. The microgrooves can increase the effective bonding area and provide multi-directional resistance to forces applied to the shaft. In some embodiments, the features comprise a ferrule including a weighting feature that replaces a tip weight. In some embodiments, the features comprise a hot melt weight located within the shaft.

CROSS REFERENCE PRIORITIES

This claims the benefit of U.S. Provisional Application No. 63/217,683, filed Jul. 7, 2021, and U.S. Provisional Application No. 63/140,747, filed Jan. 22, 2021, the contents of which are fully incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates generally to golf clubs and relates more particularly to golf club shafts having various features which improve bonding strength.

BACKGROUND

A typical golf club comprises a shaft and a club head connected to the bottom end of the shaft, thereby forming a head-shaft connection (the “connection”). During a swing, the connection experiences multi-directional swing forces otherwise known as normal forces and torsional forces. During a swing, the club head pulls away from the shaft, thereby applying a normal force, and the club head rotates or twists relative to the shaft, thereby applying a torsional force on the connection. In addition to the swing forces, the connection experiences an impact force as it strikes the ball. To prevent club head failure, the head-shaft connection must be strong enough to withstand these applied forces.

The connection is defined where the shaft tip is received by the hosel. An epoxy material is used to secure the shaft to the club head. The epoxy material forms bonds, or micro-links between the shaft tip and the hosel. The strength of the connection relies on the effective bonding surface, or the amount of the shaft outer surface in direct contact with the hosel inner surface. The bonding strength increases as the effective bonding area increases. The connection requires sufficient effective bonding area to prevent the club head from flying off and failing catastrophically.

The effective bonding area is constrained by the shaft insertion depth and the hosel depth. In some golf clubs, the effective bonding area is further constrained by other components that are placed within the hosel such as a ferrule, an adjustable hosel sleeve, or a tip weight. These components are used to improve other characteristics of the golf club. For example, tip weights provide a means to balance the club head with the shaft to achieve a desired swing weight. However, these components require space within the hosel, which reduces the allowable effective bonding area between the shaft and the hosel. In some golf clubs, to compensate for these additional components, the hosel is made larger (longer) to achieve a sufficient effective bonding area. However, to create a larger hosel, mass must be moved from desirable locations to the hosel, which negatively impacts mass properties and sacrifices overall club head performance.

Considering the above, further developments with respect to reinforcing appropriate golf club features may enhance the performance of golf clubs while maintaining sufficient structural integrity thereof. Therefore, there is a need in the art for golf club that provides an improved bonding strength between the head and the shaft while achieving desired swing weights without negatively affecting mass properties and MOI.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exploded cross-sectional view of a golf club, according to a first embodiment.

FIG. 2A illustrates a cross-sectional view of the golf club of FIG. 1.

FIG. 2B illustrates a cross-sectional view of a golf club, according to a second embodiment.

FIG. 3A illustrates a side view of a golf club shaft comprising microgrooves, according to a first embodiment.

FIG. 3B illustrates a close up view of the microgrooves of FIG. 3A.

FIG. 4 illustrates a side view of a golf club shaft comprising microgrooves, according to a second embodiment.

FIG. 5 illustrates a side view of a golf club shaft comprising microgrooves, according to a third embodiment.

FIG. 6 illustrates a side view of a golf club shaft comprising microgrooves, according to a fourth embodiment.

FIG. 7 illustrates a side view of a golf club shaft comprising microgrooves, according to a fifth embodiment.

FIG. 8 illustrates a side view of a golf club shaft comprising microgrooves, according to a sixth embodiment.

FIG. 9 illustrates a side view of a golf club shaft comprising microgrooves, according to a seventh embodiment.

FIG. 10 illustrates a side view of a golf club shaft comprising microgrooves, according to a eighth embodiment.

FIG. 11 illustrates a perspective view of a ferrule, according to a first embodiment.

FIG. 12A illustrates a perspective view of a ferrule, according to a second embodiment.

FIG. 12B illustrates a perspective view of the internal weight of FIG. 12A.

FIG. 13A illustrates a cross-sectional view of a ferrule, according to a third embodiment.

FIG. 13B illustrates a perspective view of the weight ring of the ferrule of FIG. 13A.

FIG. 14 illustrates a side view of a ferrule, according to a fourth embodiment.

FIG. 15A illustrates an exploded view of a golf club head comprising a hot melt tip weight.

FIG. 15B illustrates a cross-sectional view of the golf club head of FIG. 15A.

Described herein is a golf club comprising various features that increase effective bonding area between the shaft and the club head without negatively affecting club head characteristics. In some embodiments, the existing hosel and tip weighting geometries are maintained such that the shaft comprises features according to aspects of the present invention, such as microgrooves. In other embodiments, these hosel and tip weighting geometries are changed such that the hosel and tip weights are modified to either include features, such as weighted ferrules, or be replaced by the features, such as hot melt tip weights.

In some embodiments, and as mentioned above, the features to increase the effective bonding area between the shaft and the golf club head include microgrooves. The microgrooves increase the connection strength in several ways. First, the microgrooves are recessed into the shaft and define a plurality of side walls, which increase effective bonding area. The side walls and the floor of the microgrooves provide more surface area than a flat shaft surface. Additional bonding area increases the bonding strength because the epoxy has more surface area to form bonds between the hosel and shaft. Second, the microgrooves form pathways or channels that promote even epoxy flow around the shaft tip, which prevents pressure buildups and air pockets between the hosel, and the remaining part of the golf club head. Last, the side walls of each microgroove can be oriented in different directions to provide more resistance to normal and/or torsional forces. The microgrooves create pathways to distribute stress more evenly throughout the connection. In some embodiments the microgrooves can be discrete lines, discrete shapes, intersecting lines, or intersecting shapes. The microgrooves can extend circumferentially around the effective bonding area, or they may be formed in groups. The groups comprise a plurality of microgrooves having various shapes. The microgrooves can be formed in various patterns that define the group. The microgroove side walls can be smooth or jagged. The microgrooves can be applied to the shaft tip end, the shaft butt end, or the grip inner surface. The microgrooves can include other features such as ridges, cutouts, roughness zones, or any other feature that increase the roughness of the effective bonding area.

In other embodiments, and as mentioned above, the features to increase the effective bonding area between the shaft and the golf club head include weighting elements that replace traditional perimeter and swing weighting elements, such as a tip weight. Removing the tip weight allows the shaft to be inserted further into the hosel, thereby maximizing the shaft insertion depth. These weighting elements can be used in combination with a smaller tip weight. In some embodiments, the weighting element is a ferrule comprising a weight. The weight can be visible from an exterior side of the ferrule, or the weight can be hidden within the ferrule. In an alternative embodiment, the ferrule is formed from a high-density material. In another embodiment, the weighting element is a hot melt weight located within the shaft body. These weighting elements provide substantial mass to weight the club head, thereby allowing the tip weight to be removed or replaced with a smaller tip weight. The weighting elements described herein maximize the effective bonding area to strengthen the head-shaft connection.

The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein are intended to be open-ended transitional phrases, terms or words that do not preclude the possibility of additional acts or structures. The singular forms “a,” “and” and “the” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of” and “consisting essentially of” the embodiments or elements presented herein, whether explicitly set forth or not.

The term “approximately” as used hereinafter in the disclosure below is used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, it includes at least the degree of error associated with the measurement of the particular quantity). The modifier “approximately” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from approximately 2 to approximately 4” also discloses the range “from 2 to 4.” The term “approximately” may refer to plus or minus 10% of the indicated number. For example, “approximately 10%” may indicate a range of 9% to 11%, and “approximately 1” may mean from 0.9-1.1. Other meanings of “approximately” may be apparent from the context.

The terms “first,” “second,” “third,” “fourth,” as used hereinafter in the disclosure below is used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.

The terms “circumferentially,” “parallel,” “non-parallel,” “perpendicular,” “non-perpendicular,” as used hereinafter in the disclosure below is used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the apparatus, methods, and/or articles of manufacture described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

“Bonding strength” as used herein can be the strength of epoxy material at the head-shaft connection or the grip-shaft connection. The bonding strength can be quantified by the energy required to break the bonds between the bonding surface and the hosel inner surface or the grip inner surface.

“Coordinate System” as used herein comprises a loft plane tangent to the geometric center of the strike face. The club head defines a ground plane tangent to the sole when the club head is at an address position. The coordinate system is defined by an origin at a geometric center of a golf club head strike face. The face center of the strike face defines an origin for a coordinate system having an x-axis, a y-axis, and a z-axis. The x-axis is a horizontal axis that extends through the face center in a direction extending from near the heel to near the toe parallel to the ground plane. The y-axis is a vertical axis that extends through the face center in a direction extending from near the sole to near the crown perpendicular to the ground plane. The y-axis is perpendicular to the x-axis. The z-axis is a horizontal axis that extends through the face center in a direction extending from near the front to near the rear parallel to the ground plane. The z-axis is perpendicular to the x-axis and the y-axis. The x-axis extends in a positive direction toward the heel. The y-axis extends in a positive direction toward the crown. The z-axis extends in a positive direction toward the rear.

“Center of Gravity Coordinate System” as used herein defined at a center of gravity of a golf club head. The center of gravity is located within the coordinate system defined above. The center of gravity can have a location on the x-axis, the y-axis, and the z-axis. The center of gravity further defines an origin of coordinate system having a CG x-axis, a CG y-axis, and a CG z-axis. The CG x-axis extends through the CG from near the heel to near the toe. The CG y-axis extends through the CG from near the crown to near the sole, the CG y-axis is perpendicular to the CG x-axis. The CG z-axis extends through the CG from near the front to near the rear, perpendicular to both the CG x-axis and the CG y-axis.

“Effective bonding area” as used herein can be a surface area of the shaft outer surface that is in direct contact with the hosel bore inner surface. The effective bonding area can extend circumferentially around the shaft outer surface and can be located along the effective bonding depth. The effective bonding area can be located within the shaft bonding area. FIG. 2A illustrates one exemplification of the effective bonding area 154.

“Effective bonding depth” as used herein can be the depth of the shaft outer surface that is in direct contact with the hosel bore inner surface. FIG. 2A illustrates one exemplification of the effective bonding depth 156, where the effective bonding depth 156 can be measured along the longitudinal axis 110 from the ferrule bottom edge 2012 to the shaft bottom end 144. FIG. 2B illustrates another exemplification of the effective bonding depth 156, where the effective bonding depth 156 is measured along the longitudinal axis 110 from the ferrule bottom edge 2012 to the tip weight 192.

“Epoxy” as used herein can be any adhesive or resin mixture used to bond the shaft to the club head or grip. The epoxy may be applied to the shaft bonding area and used as means to secure the connection. The epoxy may form bonds between the shaft bonding area and the hosel inner surface or the grip inner surface.

“Ferrule depth” as used herein can be the length of the ferrule lower portion or centering region that enters the hosel. FIG. 2A illustrates one exemplification of the ferrule depth 2030, where the ferrule depth 2030 is measured along the longitudinal axis 110 from the ferrule ledge 2018 to the ferrule bottom edge 2012.

“Ferrule surface” as used herein can be the surface area of the ferrule lower portion that contacts the hosel bonding area. FIG. 2A illustrates one exemplification of the ferrule surface 2046, where the ferrule surface 2046 extends circumferentially around the ferrule lower portion and is located at the ferrule depth 2030.

“Golf club” as used herein can be an iron-type golf club, a wood-type golf club, or a putter-type golf club. An iron-type golf club can be a cavity, cavity back, hollow body, forged, casted, cross over golf club head. A wood-type golf club can be a driver, fairway, or hybrid type golf club head.

“Head-shaft connection” as used herein can be the connection between the shaft tip outer surface and the inner surface of the hosel. The connection can be used interchangeably with the “connection.”

“Hosel bonding area” as used herein can be the surface area of the hosel bore inner surface that bonds with the shaft. FIG. 1 illustrates one exemplification of the hosel bonding area 138, where the hosel bonding area 138 extends circumferentially around the hosel bore inner surface and is located along the hosel depth 134.

“Hosel depth” as used herein can be the total depth of the hosel bore measured along the longitudinal axis. FIG. 1 illustrates one exemplification of the hosel depth 134, where the hosel depth 134 is measured from the hosel bore rim 126 to the hosel bore base 128.

“Iron-type golf club head” as used herein comprise a top rail, a sole, a heel, a toe, a rear, and a strike face. Generally, iron-type golf club heads comprise one integral body wherein the strike face and hosel are formed together. In other embodiments the strike face can be formed separately.

“Longitudinal axis” as used herein can be the axis extending from a geometric center of the shaft top end to a geometric center of the shaft bottom end. The shaft can be a symmetrical cylinder that is bisected by the longitudinal axis.

“Moment of Inertia” as used herein can be a moment of inertia Ixx and/or Iyy. The moment of inertia Ixx is defined about the CG x-axis (i.e., crown-to-sole moment of inertia) and the moment of inertia Iyy is defined about the CG y-axis (i.e., heel-to-toe moment of inertia). The moment of inertia represents the ability for the golf club head to resist twisting.

“Normal force” as used herein can be a pulling force applied normal or perpendicular to the cross-sectional area of the shaft. In other words, the normal force can be applied parallel to the shaft longitudinal axis. The normal force may be used interchangeably with the “pushing force” or “pulling force”. The normal force may be applied to a shaft and cause a uniform normal stress over the object's cross-sectional area.

“Shaft bonding area” as used herein can be the surface area of the shaft that bonds with the hosel bore inner surface. The shaft bonding area can extend circumferentially around the shaft outer surface and can be located at the shaft insertion depth. FIG. 1 illustrates one exemplification of a shaft bonding area 150, where the shaft bonding area 150 includes the effective bonding area 154 and the ferrule outer surface 2046.

“Shaft insertion depth” as used herein can be the depth of the shaft that is inserted into the hosel bore. FIG. 1 illustrates one exemplification of the shaft insertion depth 152, where the shaft insertion depth 152 is measured along the longitudinal axis 110 from the shaft tip end 144 to the ferrule ledge 2018.

“Tip weight” as used herein can be a cylindrical weighting component that can be inserted into the hosel and held into place with an epoxy material. The tip weight can be formed from a high-density material. FIG. 2B illustrates one exemplification of a tip weight 190 located near the hosel base 128 and comprising a tip weight depth 192 measured along the longitudinal axis 110.

“Torsional force” as used herein can be a twisting force applied parallel or tangent to the cross-sectional area of the shaft. In other words, the torsional force can be applied perpendicular to the shaft longitudinal axis. The torsional force may mean be used interchangeably with the torque or twisting force. The torsional force may be applied to a shaft and cause a distribution of shear stress over the shaft's cross-sectional area.

“Transition step” as used herein can be a transition region located on the shaft outer surface near the bottom end. The transition step can be defined as the transition between the shaft bonding surface and the remainder of the shaft located above the shaft bonding area. In some embodiments, the transition step can be defined by a change of surface finishes. For example, the portion of the shaft above the transition step can have a glossy finish, and the portion of the shaft below the transition step can have a sand blasted finish. In other embodiments, the transition step can be defined by a change in the outer diameter of the shaft. For example, the portion of the shaft above the transition step can have a larger diameter than the portion of the shaft below the transition step.

“Wood-type golf club head” as used herein can comprise a strike face and a body secured together to define a substantially closed/hollow interior volume. The club head comprises a crown, a sole opposite the crown, a heel, a toe opposite the heel, a front, and a rear opposite the front. The body can further include a skirt or trailing edge located between and adjoining the crown and the sole, the skirt extending from near the heel to near the toe of the club head.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials similar or equivalent to those described herein can be used in practice or testing of the present invention. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

DETAILED DESCRIPTION

Described herein is a golf club including features that increase bonding strength between the club head and the shaft. Bonding strength is increased when the effective bonding area is increased, and when the epoxy is able to flow evenly around the shaft. This can be achieved by maintaining current hosel and ferrule geometries while also increasing bonding surface area or by modifying the ferrule so that current features may be removed, thereby increasing shaft insertion depth and bonding surface area.

The golf club described herein comprises a club head 100, a shaft 140, and a grip 160. The club head 100 comprises a body 120 and a hosel 122, where the hosel 122 comprises a hosel bore 124. The hosel bore 124 is defined by an inner surface that extends from a hosel rim 126 to a hosel base 128. The inner surface defines a hosel bonding area 138 that interacts with the shaft 140. The hosel bonding area 138 is the inner surface of the holes 122 which is used bond the hosel 122 to the shaft 140. The shaft 140 comprises a top end 142 that is received within the grip 160, a bottom end 144 that is received within the hosel bore 124, and an outer surface 146. The outer surface 146 defines transition step 148 and a shaft bonding area 150 near the bottom end 144. The shaft bonding area 150 is the surface of the shaft 140 which is used to bond the shaft 140 to the hosel 122. The shaft bottom end 144 is located within the hosel bore 124 such that the shaft bonding area 150 contacts the hosel bonding area 138. The interaction between the shaft bonding area 150 and the hosel bonding area 138 form the connection between the club head 120 and the shaft 140. Further, the configurations of the shaft bonding area 150 and the hosel bonding area 138 determine the strength of the head-shaft connection.

The portion of the shaft bonding area 150 in direct contact with the hosel bonding area 138 is known as the effective bonding area 154. In most embodiments, the effective bonding area 154 is smaller than the shaft bonding area 150 and is restricted due to the presence of other components within the hosel bore. As discussed above, it is desirable to maximize the effective bonding area 154 to strengthen the head-shaft connection. One way of maximizing the effective bonding area 154 is to increase the effective bonding depth 156 by removing the additional components. The maximum effective bonding depth 156 is equal to the shaft insertion depth 152, where the effective bonding area 154 equals the shaft bonding area 150. In such an embodiment, the entire shaft bonding area 150 directly contacts the hosel bonding area 138. In other embodiments in which the additional components are present, the effective bonding area 154 is maximized while remaining within the existing footprint.

For example, some golf clubs further comprise a ferrule 2000 located around the shaft 140. Referring to FIG. 2A, the ferrule 2000 comprises a lower portion that is inserted into the hosel bore 124 at a ferrule depth 2030. The lower portion of the ferrule 2000 comprises an outer surface 2046 that contacts the hosel bonding area 138, which prevents the shaft bonding area 150 (at the ferrule depth 2030) from contacting the hosel bonding area 138. The effective bonding depth 156 is thereby reduced by the ferrule depth 2030. In other embodiments, the golf club further comprises a tip weight 190 that sits at the hosel bore base 128. The tip weight 190 consumes space within the hosel bore 124, thereby reducing the allowable shaft insertion depth 152. The effective bonding area 154 is reduced by the tip weight depth 192. The present disclosure describes several features designed to increase the effective bonding area 154 to increase bonding strength between the club head 100 and the shaft 140. The golf club described herein can comprise any combination of these features.

A. Golf Club Shaft Having Microgrooves

As described below, the shaft 140 can comprise a plurality of microgrooves. The microgrooves increase the effective bonding area 154 without increasing the effective bonding depth 156. The microgrooves can be used to improve the bonding strength while keeping other desirable hosel features such as a ferrule, tip weight, and hosel size.

Referring to FIGS. 3A-10, the golf club shaft 140 can further comprise a plurality of microgrooves. In some embodiments, the microgrooves are located within the shaft bonding area 150. In other embodiments, the microgrooves are located only within the effective bonding area 154. The microgrooves reinforce the head-shaft connection by increasing the effective bonding area and providing multi-directional resistance to forces. The microgrooves are recessed into the shaft and define a plurality side walls, where the side walls each define a depth of the microgrooves and a side wall surface area. The side wall surface areas provide additional area to the effective bonding area 154. Therefore, the microgrooves increase the effective bonding area 154 without increasing the effective bonding depth 156. The microgrooves are formed integrally with the shaft 140, which makes the microgrooves a universal feature that can be applied to any shaft 140 without changing the existing footprint of the shaft 140 and/or the hosel features. In some embodiments, the microgrooves can have two sidewalls and a planar floor that define a U-shaped channel in a cross-sectional view. In other embodiments, the microgrooves can have two angled sidewalls that connect to from a V-shape channel.

In addition to increasing the effective bonding area 154, the microgrooves are oriented such that the side walls provide resistance to the different forces that are applied to the shaft 140 (and the head-shaft connection) during the swing and on impact with a golf ball. During the downswing, the shaft 140 experiences normal forces that are applied parallel to the longitudinal axis 110 in a direction from the butt end to the tip end of the shaft 140 such that the club head is pulled apart from the shaft. The shaft 140 further experiences torsional forces that are applied perpendicular to the longitudinal axis 110 upon impact with a golf ball such that the golf club head will rotate about the shaft axis. The microgroove side walls provide resistance when oriented in a direction that is non-parallel to the applied force. In other words, the microgroove side walls provide resistance to normal forces when oriented non-parallel to the longitudinal axis 110 and provide resistance to torsional forces when oriented non-perpendicular to the longitudinal axis 110.

The microgrooves each define a depth, measured from the shaft outer surface 146 to a floor of each microgroove. The microgroove depth may alternatively be described as the height of the microgroove side walls. In some embodiments, the side walls are perpendicular to the shaft outer surface 146. In other embodiments, the side walls are angled relative to the shaft outer surface 146. The microgrooves depth correlates to the side wall surface area and the increase in the effective bonding area 154. The same amount of force applied to a larger surface area will have a lower effect as the force is more distributed. Therefore, the microgroove depth is maximized to improve bonding characteristics. However, the microgroove depth is controlled by the thickness of the shaft 140. The microgroove depth is restricted to prevent the microgrooves from penetrating too deep, which can compromise the strength of the shaft 140.

Additionally, the microgrooves provide epoxy pathways or channels that extend circumferentially around the shaft outer surface 146. These channels promote even epoxy flow around the shaft 140 which maximizes the surface covered by epoxy and further increases bonding strength. Therefore, the microgrooves consider multi-directional forces while maximizing the effective bonding area 154 and promoting even epoxy coverage. In some embodiments, the microgroove side walls are oriented in a direction that is non-parallel and non-perpendicular to the longitudinal axis 110, as defined above, thereby providing resistance to both normal and torsional forces.

The microgrooves can be formed in any combination of discrete or intersecting shapes, wherein each shape comprises at least three side walls. The microgrooves can be formed in groups of at least two microgrooves. However, each group can comprise one, two, three, four, five, six, seven, eight, nine, or ten or more microgrooves. Further, the microgrooves can be formed in one, two, three, four, five, six, seven, eight, nine, or ten or more groups of microgrooves. The microgrooves can be formed as a plurality of discrete or intersecting lines. Alternatively, the microgrooves can be formed as a plurality of randomly oriented elements. The microgrooves may be formed in any combination as described herein. However, the microgrooves may preferably be formed such that they provide resistance to both normal and torsional forces. The positioning and sizing of the microgrooves are selected to reinforce the head-shaft connection without compromising the strength of the shaft. As discussed below, the microgrooves can be formed in various shapes and lines with varying sizes.

The microgroove depth is between 0.0010 inch to 0.0050 inch. In some embodiments, the microgroove depth is less than approximately 0.0010 inch, 0.0015 inch, 0.0020 inch, 0.0025, 0.0030 inch, 0.0035 inch, or 0.0040 inch. In some embodiments, the microgroove depth is between 0.0010 inch to 0.0025 inch, 0.0010 inch to 0.0050 inch, 0.0015 inch to 0.0030 inch, 0.0025 inch to 0.0040 inch, or 0.0035 inch to 0.0050 inch. In one exemplary embodiment, the microgroove depth is 0.0030 inch. The microgrooves can be applied to both graphite and steel shafts. In some graphite shafts, the microgrooves are recessed into an outer resin layer of the shaft 140, but do not penetrate an inner composite layer.

In some embodiments, the microgroove depth is constant throughout the microgrooves, while in other embodiments, the microgroove depth varies throughout the microgrooves. In some embodiments, the microgroove depth varies such that the microgrooves are deeper near the shaft bottom end 144, and the microgrooves become shallower towards the shaft top end 142. Conversely, in other embodiments, the microgroove depth varies such that the microgrooves are deeper near the shaft top end 142, and the microgrooves become shallower towards the shaft bottom end 144. The microgroove depth can vary in any pattern, or the microgroove depth can vary randomly. Further, the depth can also vary within each individual microgroove in any direction.

The microgroove depth can be tailored to provide microgrooves having more force resistance to certain portions of the shaft bonding area 150. For example, the shaft 140 may experience an uneven stress distribution from an applied torsional force, so deeper microgrooves can be positioned where the effective bonding area 154 experiences more stress. For example, the shaft 140 may experience more stress from torsional forces at the top end of the shaft bonding area 150 than the bottom end of the shaft bonding area 150, and therefore would benefit from deeper microgrooves at the top end of the shaft bonding area 150 than the bottom end of the shaft bonding area 150. The microgroove depth is optimized to increase the effective bonding area 154 without compromising the strength of the shaft 140. The microgroove length and width are similarly selected to provide more force resistance to portions of the effective bonding area 154.

The microgrooves each further define an individual microgroove length measured along the longitudinal axis 110 from the point of the microgroove closest to the shaft bottom end 142 to the point closest to the shaft top end 144. Each microgroove further comprises an individual microgroove width measured circumferentially around the shaft 140 in a direction perpendicular to the longitudinal axis 110. The individual microgroove lengths and widths determine the increase in the effective bonding area 154.

In some embodiments, the individual microgroove length is constant throughout the microgrooves, while in other embodiments, the individual microgroove length varies throughout the microgrooves. In some embodiments, the individual microgroove length is less than 0.05 inch, 0.10 inch, 0.25 inch, 0.50 inch, 0.75 inch, 1.00 inch, 1.25 inches, 1.50 inches, 1.75 inches, 3.00 inches, 3.50 inches, or 5.00 inches. In some embodiments, the individual microgroove length is between 0.05 inch to 0.10 inch, 0.075 inch to 0.125 inch, 0.075 inch to 0.20 inch, 0.25 inch to 0.50 inch, 0.50 inch to 1.00 inch, 0.75 inch to 1.50 inches, 1.10 inches to 1.50 inches, 1.25 inches to 3.00 inches, or 2.00 inches to 5.00 inches. In one exemplary embodiment, the individual microgroove length is 0.75 inches. The microgrooves can comprise the same length, or different lengths as the adjacent microgrooves. The individual microgroove length can be tailored to provide microgrooves having more force resistance to certain portions of the shaft bonding area 150. For example, longer microgrooves can be positioned where the shaft 140 experiences more stress.

In some embodiments, the individual microgroove width is constant throughout the microgrooves, while in other embodiments, the individual microgroove width varies throughout the microgrooves. In some embodiments, the individual microgroove width is less than 0.05 inch, 0.10 inch, 0.25 inch, 0.50 inch, 0.75 inch, or 1.00 inch. In some embodiments, the individual microgroove width is between 0.05 inch to 0.50 inch, 0.075 inch to 0.125 inch, 0.075 inch to 0.20 inch, 0.25 inch to 0.50 inch, 0.30 inch to 0.75 inch, 0.50 inch to 1.00 inch, 0.75 inch to 1.50 inches, or 1.00 inch to 2.00 inches. In one exemplary embodiment, the individual microgroove width is 0.015 inch. The microgrooves can comprise the same width, or different widths as the adjacent microgrooves. The individual microgroove width can be tailored to provide microgrooves having more force resistance to certain portions of the shaft bonding area 150. For example, wider microgrooves can be positioned where the shaft 140 experiences more stress.

The surface areas of each of the microgroove side walls are determined by the depth, length, and width of each microgroove. The microgroove side walls increase the effective bonding area 154, which increases bonding strength by providing additional surface area for the epoxy to bond. In some embodiments, the microgrooves increase the effective bonding area 154 by more than 0.01 in², 0.05 in², 0.10 in², 0.25 in², 0.50 in², 0.75 in², 1.00 in², 1.25 in², or 1.50 in². In some embodiments, the microgrooves increase the effective bonding area 154 by more than 5%, 10%, 15%, 20%, 30%, 50%, 75%, or 90%. In other embodiments, the microgrooves increase the effective bonding area 154 by between 5% to 10%, 5% to 15%, 10% to 25%, 25% to 50%, 50% to 75%, or 75% to 90%. The microgrooves form micro-channels that increase the effective bonding area 154. The increase in the effective bonding area 154 strengthens the bonding strength at the head-shaft connection by providing more surface area for additional bonds to form.

The microgrooves further comprise a total depth measured along the longitudinal axis from the microgroove nearest the shaft bottom end 144 to the microgroove nearest the shaft top end 142. The total microgroove depth is different from the individual microgroove depth. The total microgroove depth is the actual length of the shaft that comprises microgrooves. In some embodiments, the microgrooves cover the entire shaft bonding area 150, where the total microgroove depth is equal to the shaft insertion depth. In other embodiments, the microgrooves are located only in the effective bonding area 154, where the total microgroove depth is equal to the effective bonding depth 156. In some embodiments, the total microgroove depth is greater than 0.90 inches, 1.00 inches, 1.10 inches, 1.20 inches, 1.30 inches, or 1.35 inches. In some embodiments, the total microgroove depth is between 0.50 inches to 1.00 inches, 0.50 inches to 1.50 inches, 0.60 inches to 0.90 inches, 0.70 inches to 1.10 inches, 0.80 inches to 1.10 inches, 1.20 inches to 1.75 inches, 1.50 inches to 3.00 inches, or 2.50 inches to 5.00 inches. In one exemplary embodiment, the total microgroove depth is 1.10 inches.

The total microgroove depth determines the portion of the shaft bonding area 150 that is covered by microgrooves. In some embodiments, the microgrooves cover between 10% to 20%, 25% to 50%, 25% to 75%, 30% to 80%, 50% to 70%, 50% to 90%, 60% to 100%, or 75% to 100% of the shaft bonding area 150. The microgrooves are formed in a continuous pattern without large spacing in between adjacent microgrooves. In some embodiments, the microgrooves are distributed evenly, while in other embodiments, the microgrooves are concentrated throughout portions of the shaft bonding area 150. The sizing of the microgrooves is selected to increase the effective bonding area 154 without compromising the strength of the shaft 140. The microgroove sizing and shaping discussed above can be applied to the various embodiments of microgrooves described herein.

The golf club described herein can comprise any combination of the microgroove patterns as described below. In some embodiments, the microgrooves are formed as lines, while in other embodiments, the microgrooves are formed in shapes. As discussed above and in some embodiments, each microgroove is recessed into the shaft 140 defined by a plurality of side walls (or “side walls”) and a planar floor. In other embodiments, the microgrooves are recessed into the shaft 140 defined by two sides walls forming a V-shape or U-shape channel. The orientation of the side wall is described relative to the longitudinal axis 110. The side walls can be oriented horizontal (perpendicular to the longitudinal axis 110), vertical (parallel to the longitudinal axis 110), or diagonal (angled relative to the longitudinal axis 110) relative to the longitudinal axis 110. The orientation of the microgrooves is selected to provide multi-directional resistance to the applied forces on a golf club shaft. Each side wall can be a smooth continuous surface, or the side walls can be jagged. Further, the microgrooves can intersect, or can be discrete lines.

I. Microgrooves Formed in Lines

In some embodiments, the microgrooves can be formed as a plurality of lines, as shown in FIGS. 3A-8. The microgrooves 1100, 1200, 1300, 1400, 1500 are described using similar reference numbers. For example, the microgrooves 1100, 1200, 1300, 1400, 1500 comprise side walls 1110, 1210, 1310, 1410, 1510 and floors 1120, 1220, 1320, 1420, 1520.

In some embodiments (see FIGS. 3A and 3B), the microgrooves 1100 can extend circumferentially around the shaft 140 in a direction diagonal to the longitudinal axis 110 such that the direction is not perpendicular or parallel. In other words, the microgrooves 1100 spiral around the shaft. The microgrooves 1100 have a first group 1130 and a second group 1140. The first group 1130 of microgrooves 1100 spirals around the shaft clockwise in a top to bottom direction. The second group 1140 of microgrooves 1100 spirals around the shaft counterclockwise in a direction top to bottom. The first and second group 1130, 1140 of microgrooves 1100 intersect forming diamond shaped protrusions between the microgrooves 1100.

The microgrooves 1100 form an angle with the longitudinal axis 110. The angle is measured from the longitudinal axis to a side wall 1110 of the microgroove 1100. The angle can range from greater than 0 degrees to less than 90 degrees, in a direction measured clockwise or counterclockwise from the longitudinal axis 110. For example, one set of microgrooves 1100 form an angle of 45 degrees measured in a clockwise direction and a second set of microgrooves from an angle of 45 degrees measured in a counterclockwise direction, as illustrated in FIGS. 3A and 3B. In other embodiments, the microgrooves can from an angle of 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, or 85 degrees measured in a clockwise or counterclockwise direction with the longitudinal axis 110.

In other embodiments, the microgrooves 1200 can extend circumferentially around the shaft 140 in a direction perpendicular to the longitudinal axis 110 such that they do not intersect, as shown in FIG. 4. The side walls 1210 are parallel to one another, and perpendicular to the longitudinal axis 110. The side walls 1210 provide resistance to normal forces.

In another embodiment, the microgrooves 1300 can extend in a direction parallel to the longitudinal axis 110, as shown in FIG. 5. The microgrooves 1300 are positioned circumferentially around the shaft 140 and do not intersect. The side walls 1310 are parallel to one another and parallel to the longitudinal axis 110. The side walls 1310 provide resistance to torsional forces.

In another embodiment, the microgrooves can comprise a first plurality of microgrooves 1200 and a second plurality of microgrooves 1300, as shown in FIG. 6. The side walls 1210 of the first plurality of microgrooves 1200 are parallel to one another and perpendicular to the longitudinal axis 110, and the side walls 1310 of the second plurality of microgrooves 1300 are parallel to one another and parallel to the longitudinal axis 110. The first plurality of microgrooves 1200 can be located above, or closer to the shaft top end 142 than the second plurality of microgrooves 1300. The first plurality of microgrooves 1200 can also be located below the second plurality of microgrooves 1300, as illustrated in FIG. 6. The microgrooves 1200, 1300 provide resistance to normal and torsional forces.

The first plurality of microgrooves 1200 and the second plurality of microgrooves 1300 each comprise at least one microgroove. In some embodiments, the first and second plurality of microgrooves 1200, 1300 each comprise between 10 to 20 microgrooves, 20 to 50 microgrooves, 10 to 30 microgrooves, 30 to 70 microgrooves, 50 to 100 microgrooves, 40 to 60 microgrooves, 50 to 150 microgrooves, or 30 to 50 microgrooves. In other embodiments, the microgrooves can further comprise a third plurality of microgrooves, a fourth plurality of microgrooves, or a fifth plurality of microgrooves.

In another embodiment, the microgrooves 1400 can extend circumferentially around the shaft 140 in a direction perpendicular to the longitudinal axis 110 such that they do not intersect, as shown in FIG. 7. The side walls 1410 define jagged or not straight side wall sections 1410. Each side wall section 1410 is angled with respect to the adjacent side wall section 1410. Further, each side wall section 1410 is oriented non-parallel and non-perpendicular to the longitudinal axis 110. The angle side wall sections 1410 provide resistance to normal and torsional forces.

In another embodiment, the microgrooves 1500 can extend circumferentially around the shaft 140 in a diagonal direction relative to the longitudinal axis 110, as shown in FIG. 8. In this embodiment, the microgrooves 1500 are generally parallel to each adjacent microgroove 1500. The microgrooves 1500 are similar to the microgrooves 1400 shown in FIG. 7, where the side walls 1510 define side wall sections 1510. The side wall sections 1510 are angled with respect to the adjacent side wall sections 1510. Further, each side wall section 1510 is oriented non-parallel and non-perpendicular to the longitudinal axis 110. The angled side wall sections 1510 provide resistance to normal and torsional forces.

II. Microgrooves Formed in Shapes

In some embodiments, the microgrooves are formed as a plurality of shapes, as shown in FIGS. 9 and 10. The microgrooves 1600, 1700 are described using similar reference numbers. For example, the microgrooves 1600, 1700 comprise side walls 1610, 1710 and floors 1620, 1720. As discussed above, each microgroove is recessed into the shaft 140 via a plurality of side walls (or “side walls”) and a floor. The side walls define the shape of the microgrooves.

Each microgroove defines a shape that can be the same or different than the rest of the microgrooves. The microgrooves can be any combination of circles, lines, triangles, squares, rectangles, polygons, or any suitable shape. The microgrooves can intersect or overlap, or the microgrooves can be discrete shapes. The microgrooves can be formed in rows, or the microgrooves can be formed in groups.

The groups of microgrooves are defined by a collection of closely packed microgrooves. The groups of microgrooves can be evenly spaced, or the spacing can vary. Further, the microgrooves within each group can be evenly spaced, or the spacing can vary. The spacing and density of microgrooves within each group and across all groups can be selected such that the microgrooves may provide more normal or torsional force resistance to portions of the shaft 140.

Similar to the groups of microgrooves, the microgrooves can be organized in rows. The rows of microgrooves can be evenly spaced, or the spacing can vary. Further, the microgrooves within each row can be evenly spaced, or the spacing can vary. The spacing and density of microgrooves within each row and across all rows can be selected such that the microgrooves may provide more normal or torsional resistance to portions of the shaft 140. Each microgroove can define a shape that can be the same or different than the adjacent microgroove within the same row. Further, the microgrooves can comprise the same shape within each row, and different shapes across rows.

In some embodiments, the microgrooves 1600 can be formed in groups 1630, as shown in FIG. 9. The groups 1630 take the shape of a hexagon. Each group 1630 comprises six triangularly shaped microgrooves 1600.

In other embodiments, the microgrooves 1700 can be formed in rows 1740 that extend circumferentially around the shaft 140, as shown in FIG. 10. The microgrooves 1700 are triangular in shape. The microgrooves 1700 having varying size across the rows 1740 such that the microgrooves 1700 in the top row are smaller than the microgrooves 1700 in the bottom row.

Furthermore, the microgrooves 1600 and 1700 can be any combination of circles, lines, triangles, squares, rectangles, polygons, or any suitable shape. The side walls 1610 and 1710 can be oriented non-parallel or non-perpendicular to the longitudinal axis 110. As such, each microgroove 1600 and 1700 forms at least one of a normal resistance component or a torsional resistance component. Each group and row 1630 and 1740 can be oriented in a direction that is perpendicular to the longitudinal axis 110, or in a direction that is non-perpendicular to the longitudinal axis 110. Each group and row 1630 and 1740 can comprise at least one microgroove 1600 and 1700. For example, each group and row 1630 and 1740 can comprise one, two, three, four, five, six, seven, eight, nine, or ten or more microgrooves 1600 and 1700. Further, there can be one or more groups or rows 1630 and 1740. For example, there can be one, two, three, four, five, or six or more groups and rows 1630 and 1740. The groups and rows 1630 and 1740 can be evenly spaced, or the spacing can vary. The spacing and density of microgrooves 1600 and 1700 can be selected in order to provide more normal or torsional force resistance to portions of the shaft 140.

The golf club shaft 140 incorporating microgrooves as described herein provides advantages over shafts that are known in the art. Mainly, the microgrooves create a stronger bond between the club head and the shaft by (1) allowing the epoxy to flow evenly around the shaft tip (2) increasing the total effective bonding area (3) providing resistance to normal and torsional forces. As a traditional shaft is pressed into the hosel, the epoxy is spread unevenly around the shaft and concentrates near the bottom of the hosel. As a result, pressure can build up within the hosel creating trapped air pockets within the epoxy. These trapped air pockets can be seen by cutting open and viewing a cross section of the hosel once the shaft has been bonded. The trapped air pockets can also be seen by creating a test hosel that is made of a clear material (not to be used in an actual club) such as plastic such that you can view inside the hosel during the shaft insertion. Trapped air pockets weaken the bonding strength and are propagation points for stress fracturing. The microgrooves provide pathways for the epoxy to flow evenly around the shaft, thereby reducing pressure buildup within the hosel and greatly reducing or even elimination the porosity of air pockets. Further, the microgrooves reduce epoxy waste as less epoxy is required to create an even distribution. The side walls of the microgrooves provide additional surface area for the epoxy to form micro-links between the shaft tip and the hosel bore inner surface. Further, the side walls are oriented such that are at least non-parallel or non-perpendicular to the longitudinal axis to resist forces that are applied parallel or perpendicular to the longitudinal axis. Increasing bonding strength allows club designers to add weighting components such as tip weights to the hosel. The microgrooves compensate for the decreased bonding strength caused by the loss in shaft insertion depth. Further, the microgrooves are a universal feature that can accommodate both right-handed and left-handed clubs.

B. Golf Club Comprising Weighted Ferrule

Further described herein are various embodiments of a weighted ferrule that replace a traditional tip weight by removing mass from the tip weight and redistributing the mass to the ferrule. By removing mass from the tip weight, the tip weight can either be completely removed or greatly reduced in size. Removing the tip weight or reducing the tip weight size will allow the shaft 140 to be inserted further into the hosel bore 124 thereby increasing the effective bonding area 154 and improving bonding strength. The tip weight 190 comprises a tip weight depth 192 that reduces the allowable shaft insertion depth 152 (and the effective bonding depth 156), as shown in FIG. 2B. The tip weight depth 192 can range from 0.1 inch to 0.5 inch. For example, the tip weight depth 192 can be 0.1 inch, 0.2 inch, 0.25 inch, 0.3 inch, 0.35 inch, 0.40 inch, or 0.5 inch. In some embodiments, the tip weight 190 is used to manipulate the center of gravity (CG) of the club head 100 or adjust the swing weight of the club head 100.

Therefore, in the embodiments discussed below, the tip weight 190 can be removed or replaced with a smaller tip weight 190, which increases the shaft insertion depth 152. In some embodiments, the shaft insertion depth is increased between 0.10 inch to 0.50 inch. The increase in shaft insertion depth 152 increases the effective bonding area 154, thereby increasing the bonding strength at the head-shaft connection.

In some embodiments, referring to FIGS. 11-14, the golf club further comprises a ferrule 2000 situated around the shaft outer surface 146. The shaft bottom end 142 extends through the ferrule 2000 into the club head 120. The ferrule 2000 centers the shaft 140 within the hosel 122 and covers the blunt hosel top rim to create a smooth transition from the hosel 122 to the shaft 140. Referring to FIG. 11, the ferrule 2000 is a cylindrical body comprising a top edge 2010 proximate the grip 160, and a bottom edge 2012 proximate the club head 120. The ferrule further comprises an interior surface 2014 that contacts the shaft 140, and an exterior surface 2016 that is exposed on the exterior. The ferrule 2000 further comprises a ferrule ledge 2018 that defines a transition between an upper portion and a lower portion of the ferrule. The upper portion is a tapered region 2020 that is exposed above the hosel 122. The lower portion is a centering region 2040 that is situated within the hosel 122.

The centering region 2040 is defined between the ferrule ledge 2018 and the bottom edge 2012. The centering region 2040 is received within the hosel 122 such that the ferrule ledge 2018 is flush with the bore top rim. The centering region 2040 comprises a plurality of windows 2042 and a plurality of ribs 2044. The plurality of windows 2042 increase the pathways for excess epoxy to flow around the centering region 2040 to increase bonding strength. The plurality of ribs 2044 act as a self-centering feature. The ribs 2044 are equally spaced throughout the centering region 2040 to apply an equal amount of pressure against the hosel bore 124 to prevent the shaft 140 from entering the hosel 122 at an angle. The centering region 2040 is the lower portion of the ferrule 2000 that is received within the hosel 122, and the tapered region 2020 is the upper portion that is exposed above the hosel 122.

The tapered region 2020 is defined between the ferrule ledge 2018 and the top edge 2010. The tapered region 2020 tapers from the maximum outer diameter 2060 to a smaller diameter near the top edge 2010. The tapered region 2020 creates a smooth transition from the shaft diameter 140 to the hosel diameter 122. In some embodiments, the tapered region 2040 houses a weighting element.

The ferrule 2000 is formed from a resin that can have a density between 0.9 g/cm3 and 1.5 g/cm3. In some embodiments, the density is between 0.9 g/cm3 and 1.0 g/cm3, 1.0 g/cm3 and 1.1 g/cm3, 1.1 g/cm3 and 1.2 g/cm3, 1.2 g/cm3 and 1.3 g/cm3, 1.3 g/cm3 and 1.4 g/cm3, or 1.4 g/cm3 and 1.5 g/cm3. For example, the resin, in one embodiment, can have a density of 1.19 g/cm3. In some embodiments, the resin comprises Cellulosic Acetate Propionate (CAP) resin. The ferrule material is lightweight and does not provide a means of weighting the golf club head 120. Therefore, in some embodiments, the ferrule 2000 further comprises a weighting element. Various embodiments of weighting elements are described below. In some embodiments, the weighting element comprises a weight. In other embodiments, the weighting element comprises a ferrule formed from a high-density material.

The various embodiments of the weighting element described below are formed from a metallic material such as stainless steel, tungsten, a tungsten-Tenite Propionate (TPU) mixture, or a stainless steel-Tenite Propionate (TPU) mixture. The weighting element material is denser than the ferrule material. The density of the weighting element material is between 1 g/cm3 and 18 g/cm3. In some embodiments, the density of the weighting element material is between 1 g/cm3 and 2 g/cm3, 2 g/cm3 and 3 g/cm3s, 3 g/cm3 and 4 g/cm3, 4 g/cm3 and 5 g/cm3, 5 g/cm3 and 6 g/cm3, 6 g/cm3 and 7 g/cm3, 7 g/cm3 and 8 g/cm3, 8 g/cm3 and 9 g/cm3, 9 g/cm3 and 10 g/cm3, 10 g/cm3 and 11 g/cm3, 11 g/cm3 and 12 g/cm3, 12 g/cm3 and 13 g/cm3, 13 g/cm3 and 14 g/cm3, 14 g/cm3 and 15 g/cm3, 15 g/cm3 and 16 g/cm3, 16 g/cm3 and 17 g/cm3, or 17 g/cm3 and 18 g/cm3.

The various embodiments of the weighting element described below define a height measured along the longitudinal axis 110. The height is measured between a top perimeter of the weighting element to a bottom perimeter of the weighting element. In some embodiments, the height is between 0.3 inch to 0.7 inch. In some embodiments, the height is between 0.3 inch to 0.45 inch, 0.35 inch to 0.40 inch, 0.40 inch to 0.60 inch, 0.45 inch to 0.60 inch, 0.50 inch to 0.55 inch, 0.52 inch to 0.57 inch, 0.53 inch to 0.60 inch, or 0.54 inch to 0.60 inch. In some embodiments, the height is approximately 0.3 inch, 0.31 inch, 0.32 inch, 0.33 inch, 0.34 inch, 0.35 inch, 0.36 inch, 0.37 inch, 0.38 inch, 0.39 inch, 0.40 inch, 0.41 inch, 0.42 inch, 0.43 inch, 0.44 inch, 0.45 inch, 0.46 inch, 0.47 inch, 0.48 inch, 0.49 inch, 0.5 inch, 0.51 inch, 0.52 inch, 0.53 inch, 0.54 inch, 0.55 inch, 0.56 inch, 0.57 inch, 0.58 inch, 0.59 inch, 0.6 inch, 0.61 inch, 0.62 inch, 0.63 inch, 0.64 inch, 0.65 inch, 0.66 inch, 0.67 inch, 0.68 inch, 0.69 inch, or 0.7 inch.

The various embodiments of the weighting element described below further define a thickness, measured between the interior surface to the exterior surface of the weighting element. In some embodiments, the thickness remains constant throughout the weighting element, while in other embodiments, the thickness varies throughout the weighting element. The thickness is between 0.01 inch to 0.09 inch. In some embodiments, the thickness is between 0.01 inch to 0.05 inch, 0.01 inch to 0.07 inch, 0.03 inch to 0.08 inch, 0.04 inch to 0.09 inch, or 0.05 inch to 0.09 inch. In some embodiments, the thickness is approximately 0.01 inch, 0.02 inch, 0.03 inch, 0.04 inch, 0.05 inch, 0.06 inch, 0.07 inch, 0.08 inch, or 0.09 inch. In one exemplary embodiment, the thickness near the top perimeter is 0.031 inch, and the thickness near the bottom perimeter is 0.062 inch. In another exemplary embodiment, the thickness near the top perimeter is 0.021 inch, and the thickness near the bottom perimeter is 0.055 inch.

The ferrule 2000 comprising a weighting element and resin material defines a mass between 1 gram to 12 grams. In some embodiments, the mass is between, 1 gram to 5 grams, 2 grams to 7 grams, 3 grams to 6 grams, 5 grams to 10 grams, or 6 grams to 12 grams. In other embodiments, the mass is 1 gram, 2 grams, 3 grams, 4 grams, 5 grams, 6 grams, 7 grams, 8 grams, 9 grams, 10 grams, 11 grams, or 12 grams. The mass of the ferrule 2000 is selected to provide a substantial weighting element to the club head to manipulate the club head CG and/or to achieve desired swing weights.

The ferrule 2000 comprising a weighting element and a resins material further defines an average density ranging from 1 g/cm3 to 6 g/cm3. The average density is the ratio between the total mass of the ferrule 2000 and the total volume of the ferrule 2000. For example, the average density can be 2.95 g/cm3. In other embodiments, the ferrule 2000 can have an average density can be 1 g/cm3, 1.5 g/cm3, 2 g/cm3, 2.5 g/cm3, 3 g/cm3, 3.5 g/cm3, 4 g/cm3, 4.5 g/cm3, 5 g/cm3, 5.5 g/cm3, or 6 g/cm3.

The ferrule 2000 comprising a weighting element and resin material has a percent increase in mass over a ferrule comprising only a resin material between 300% and 2500%. In some embodiments, the percent increase in mass in between 300% to 400%, 400% to 500%, 500% to 600%, 600% to 700%, 700% to 800%, 800% to 900%, 900% to 1000%, 1000% to 1100%, 1100% to 1200%, 1200% to 1300%, 1300% to 1400%, 1400% to 1500%, 1500% to 1600%, 1600% to 1700%, 1700% to 1800%, 1800% to 1900%, 1900% to 2000%, 2000% to 2100%, 2100% to 2200%, 2200% to 2300%, 2300% to 2400%, or 2400% to 2500%.

The weighting element can be an internal weight located between a ferrule inner surface and the shaft, a weighted ring that extends circumferentially around the ferrule exterior surface, or a ferrule made of a high-density material. The weighting element replaces a traditional tip weight by removing mass from the tip weight and redistributing the mass to the ferrule. By removing mass from the tip weight, the tip weight can either be completely removed or greatly reduced in size. Removing the tip weight or reducing the tip weight size will allow the shaft 140 to be inserted further into the hosel bore 124 thereby increasing the effective bonding area 154 and improving bonding strength.

I. Ferrules Comprising an Internal Weight

In one embodiment (see FIG. 12A), the ferrule 2000 comprises an internal weight 2100. The internal weight 2100 provides a substantial mass to the ferrule 2000 to create a weighting element capable of manipulating the club head CG and replacing a tip weight. Referring to FIG. 12A, the internal weight 2100 is formed integrally with the ferrule 2000 near the tapered region 2020. The internal weight 2010 extends through the entire tapered region 2020. However, in other embodiments, the internal weight 2100 extends through only a portion of the tapered region 2020.

Referring to FIG. 12B, the internal weight 2100 is cylindrically shaped and comprises a top perimeter 2110 proximate the ferrule top edge 2010 and a bottom perimeter 2120 proximate the ferrule bottom edge 2012. The internal weight 2100 further comprises an inner surface 2130 that forms a portion of the ferrule interior surface 2014, and an outer surface 2140 that contacts the ferrule 2000. The internal weight 2100 defines a gap 2150 that extends from the top perimeter 2110 to the bottom perimeter 2120. As the ferrule 2000 is pushed over the shaft 140, the gap 2150 relieves stress throughout the ferrule 2000.

The gap 2150 defines a gap width measured across the opening. The gap width ranges between 0.01 inch to 0.5 inch. In some embodiments, the gap width is between 0.01 inch to 0.05 inch, 0.02 inch to 0.04 inch, 0.03 inch to 0.07 inch, 0.04 inch to 0.09 inch, 0.05 inch to 0.10 inch, 0.10 inch to 0.25 inch, 0.15 inch to 0.45 inch, 0.20 inch to 0.40 inch, 0.25 inch to 0.50 inch, 0.30 inch to 0.5 inch, or 0.40 inch to 0.50 inch. The gap width is approximately 0.01 inch, 0.02 inch, 0.03 inch, 0.04 inch, 0.05 inch, 0.06 inch, 0.07 inch, 0.08 inch, 0.09 inch, 0.10 inch, 0.15 inch, 0.20 inch, 0.25 inch, 0.30 inch, 0.35 inch, 0.40 inch, 0.45 inch, or 0.50 inch. In one exemplary embodiment, the gap width is 0.03 inch. The gap width is selected to provide stress relief to the ferrule 2000, without significantly reducing the mass of the internal weight 2100. The dimensions of the internal weight are further selected to provide a substantial weighting feature.

The internal weight 2100 defines a height between 0.5 inch to 0.6 inch. In some embodiments, the height is between 0.50 inch to 0.55 inch, 0.52 inch to 0.57 inch, 0.53 inch to 0.60 inch, or 0.54 inch to 0.60 inch. The height is approximately 0.5 inch, 0.51 inch, 0.52 inch, 0.53 inch, 0.54 inch, 0.55 inch, 0.56 inch, 0.57 inch, 0.58 inch, 0.59 inch, 0.6 inch, 0.61 inch, 0.62 inch, 0.63 inch, 0.64 inch, 0.65 inch, 0.66 inch, 0.67 inch, 0.68 inch, 0.69 inch, or 0.7 inch. In one exemplary embodiment, the height is 0.653 inch. The internal weight 2100 is hidden within the ferrule 2000 and not exposed on the ferrule exterior surface 2016. In other embodiments, the weighting element is exposed on the ferrule exterior surface 2016.

II. Ferrules Comprising Weighted Rings

Referring to FIGS. 13A-14, in some embodiments, the ferrule 2000 can comprise one or more weighted rings. The weighted rings provide a substantial mass to the ferrule 2000 to create a weighting element capable of manipulating the club head CG and replacing a tip weight. The weighted rings are formed integrally with the ferrule 2000 and extend circumferentially around the tapered region 2020. The weighted rings can be one ring, two rings, three rings, four rings, five rings, or any other suitable number of rings. In some embodiments, the weighted rings have the same height, and in other embodiments, the weighted rings have different heights.

Referring to FIGS. 13A and 13B, the ferrule 2000 further comprises a single weighted ring 2200. The weighted ring 2200 comprises a top perimeter 2210 proximate the ferrule top edge 2010 and a bottom perimeter 2220 proximate the ferrule bottom edge 2012. The weighted ring 2200 further comprises an inner surface 2230 adjacent to the ferrule outer surface 2016, and an outer surface that forms a portion of the ferrule outer surface 2016.

Referring to FIG. 14, the ferrule 2000 further comprises two weighted rings 2300. Each weighted ring 2300 comprises a top perimeter 2310 proximate the ferrule top edge 2010 and a bottom perimeter 2120 proximate the ferrule bottom edge 2012. The weighted rings 2300 each further comprise an inner surface 2330 adjacent to the ferrule outer surface 2016, and an outer surface that forms a portion of the ferrule outer surface 2016.

III. Ferrules Formed from a High Density Material

In another embodiment, the weighting feature comprises a high-density ferrule, similar to the ferrule disclosed in previous embodiments. The ferrule can be molded with a high-density resin mixture such that the ferrule 2000 has a suitable mass to replace a tip weight. The resin mixture can comprise a combination of a resin and a filler material. In some embodiments, the resin can comprise, Cellulosic Acetate Propionate (CAP) resin. The filler material can be selected from a group consisting of steel or tungsten. The resin mixture can have a specific gravity between 1 and 9. In some embodiments, the specific gravity can be between 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, or 9 to 10.

The overall mass of the high-density ferrule can be 0.1 gram to 20 grams. For example, the high-density ferrule can range from 0.1 gram to 2 grams, 2 grams to 4 grams, 4 grams to 6 grams, 6 grams to 8 grams, 8 grams to 10 grams, 10 grams to 12 grams, 12 grams to 14 grams, 14 grams to 16 grams, 16 grams to 18 grams, 18 grams to 20 grams. The mass of the ferrule can be selected to provide a substantial weighting element.

The weighted ferrules described herein are designed to replace the tip weight 190, thereby allowing the shaft 140 to be inserted further into the hosel bore 124. The increase in shaft insertion depth 152 increases the effective bonding area 154, thereby increasing the bonding strength at the head-shaft connection. Furthermore, a ferrule 2000 comprising the weighting elements described above improves mass properties such as MOI and CG. The ferrule 2000 is located above the hosel 122 and closer to a perimeter of the club head 100 than the tip weight 190. Therefore, the ferrule 2000 shifts mass closer to a perimeter of the club head 100, thereby improving the moment of inertia (MOI) of the club head 100.

C. Golf Club Head Comprising Hot Melt Weight

Further described herein is another embodiment to provide alternative means to weight the shaft, similar to the weighted ferrule embodiment described above. In this embodiment, a hot melt weight is injected the tip of the shaft, increasing the overall weight of the shaft with added mass. As mentioned above, adding weight to the shaft allows the tip weight to be removed or to be reduced in size, increasing the overall shaft insertion depth.

In one embodiment, the club head 100 can comprise a ferrule 2000, similar to the embodiments described above. The shaft 140 can further comprise a hot melt weight 3000 and a cap 3050, as shown in FIGS. 15A and 15B. The hot melt weight 3000 can be formed inside of the shaft 140 along the longitudinal axis 110. The hot melt weight 3000 can be located within the hosel bore 124 near the shaft bottom end 144. The cap 3050 can be near the bottom end 144 to secure the hot melt weight 3000 within the shaft 140. In some embodiments, the hot melt weight 3000 can extend from the shaft bottom end 144 to the ferrule bottom edge 2012. In other embodiments, the hot melt weight can extend from the bottom end 144 to the ferrule top edge. The hot melt weight 3000 can extend from the bottom end 144 to any suitable length within the shaft 140 to form a desired mass.

The hot melt weight 3000 can partially be made of a thermoplastic polymer. For example, the hot melt weight can be made from butyl rubber (BR), hydrocarbon resins, polybutene, process oil, or any combination of thereof. In some embodiments the hot melt weight 3000 comprises 30% BR, 50% hydrocarbon resin, 15% polybutene, and 5% process oil. The hot melt can be solid at room temperature and liquid when active by a heating element. The hot melt weight 3000 is liquid when injected into the tip of the shaft and solid once cooled. The hot melt weight 3000 bonds to the inner surface of the shaft to prevent any movement of the hot melt weight within the shaft 3000.

The hot melt weight 3000 can partially be formed from a metal filler material. The metal filler material can form a portion of the composition of the hot melt mentioned above. The metal filler material can comprise any suitable dense material such as Tungsten powder. The metal filler material increases the overall density of the hot melt weight 3000 to achieve a sufficient weight such that the tip weight 190 may be replaced. The metal filler material can allow any amount of weight to be added with an accuracy of 0.1 grams.

The hot melt weight 3000 can range from 0.1 gram to 20 grams. For example, the hot metal weight 3000 can range from 0.1 gram to 2 grams, 2 grams to 4 grams, 4 grams to 6 grams, 6 grams to 8 grams, 8 grams to 10 grams, 10 grams to 12 grams, 12 grams to 14 grams, 14 grams to 16 grams, 16 grams to 18 grams, 18 grams to 20 grams.

The weighting features described herein provide several advantages over traditional perimeter weighting. Removing the tip weight allows the shaft to enter further into the hosel, increasing surface area for bonding, and lowering the amount of club head failures in the field. Further, removing the tip weight will eliminate vibrations or rattling caused by loose tip weights. These weighting features move mass closer to the perimeter than a traditional tip weight which increases MOI and creates an even more forgiving club. The filler materials used to form the weights allow any amount of weight to be added with high accuracy.

Methods

The golf club 100 described herein can be manufactured by various methods. As discussed above, the golf club 100 comprises at least a club head, a shaft, and a grip. Different embodiments of each feature can be combined to form numerous variations of the golf club 100. The shaft can comprise any one or more of the variations of microgrooves 1000, 1100, 1200, 1300, 1400, or 1500 as described above. The method of manufacture can vary for different variations of the golf club 100. Described below are example methods of manufacturing the golf club 100.

The method of manufacturing a club head 100 with microgrooves 1000, 1100, 1200, 1300, 1400, 1500 can comprise (1) forming a shaft 140 (2) etching microgrooves 1000, 1100, 1200, 1300, 1400, 1500 into the shaft (3) pouring epoxy material into the hosel bore 124 and inserting the shaft 140 into the hosel bore 124 (4) pouring epoxy material into the grip and inserting the shaft 140 into the grip. In step 1, the shaft 140 can be graphite shaft or steel shaft. The shaft is formed by warping sheets of pre-peg around a steel mandrel, coating the pre-preg material with a resin, curing the shaft 140, and removing the steel mandrel. In step 2, the shaft 140 can be rotated using a shaft spinner which allows any variation of microgrooves 1000, 1100, 1200, 1300, 1400, 1500 to be applied to the shaft. The application of microgrooves 1000, 1100, 1200, 1300, 1400, 1500 can depend on the shaft material used. For example, a 3D printer is used to etch microgrooves 1000, 1100, 1200, 1300, 1400, 1500 onto the outer resin layer. In step 3, the microgrooves 1000, 1100, 1200, 1300, 1400, 1500 formed near the tip end of the shaft allow the epoxy to flow evenly around the shaft tip which reduces pressure buildup and air pockets within the hosel.

The method of manufacturing a club head 100 with a ferrule 2000 can comprise (1) forming a weighting feature 2100, 2200, 2300 from a first material (2) forming a ferrule 2000 integrally with the weighting feature 2100, 2200, 2300 using a second material (3) inserting the shaft 140 into the ferrule 2000 (4) securing the shaft 140 and ferrule 2000 into the hosel 122 (5) blending the ferrule 2000 (6) installing a toe weight. In step 1, the first material can comprise a metal consisting of stainless steel, tungsten, a tungsten-Tenite Propionate (TPU) mixture, or a stainless steel-Tenite Propionate (TPU) mixture. In step 2, the ferrule 2000 can be injection molded around the weighting feature 2100, 2200, 2300. The second material can comprise a resin. In some embodiments the resin can consist of Cellulosic Acetate Propionate (CAP) resin. In step 3, in some embodiments, a gap 2150 relieves stress as the shaft 140 can be inserted into the ferrule 2000. In step 4, the shaft can be secured within the hosel 122 with the use of an epoxy. A plurality of ribs 2024, located on the ferrule 2000, help center the shaft 140 within the hosel 122 by applying circumferential pressure to the hosel bore 124. A plurality of windows 2042, located on the ferrule 2000, allow excess epoxy to flow around the ferrule 2000 to increase bond strength between the shaft 140 and the hosel 122. In step 5, the ferrule 2000 can be blended with acetone to ensure the ferrule 2000 can be flush with the bore top rim 126. In step 6, the toe weight can be secured with the use of a screw.

The method of manufacturing a club head 100 with a high-density ferrule (not shown) can comprise (1) forming a ferrule from a high-density resin mixture (2) inserting the shaft 140 into the ferrule (3) securing the shaft 140 and ferrule into the hosel 122 (4) blending the ferrule (5) installing a toe weight. In step 1, the ferrule can be injection molded. The resin mixture can comprise a combination of a resin and a filler material. In some embodiments, the resin can comprise Cellulosic Acetate Propionate (CAP) resin, and the filler material can be steel or tungsten. In step 3, the shaft 140 can be secured within the hosel 122 with the use of an epoxy. A plurality of ribs 2044, located on the ferrule 2000, help center the shaft 140 within the hosel 122 by applying circumferential pressure to the hosel bore 124. A plurality of windows 2042, located on the ferrule 2000, allow excess epoxy to flow around the ferrule 2000 to increase bond strength between the shaft 140 and the hosel 122. In step 4, the ferrule 2000 can be blended with acetone to ensure the ferrule 2000 can be flush with the hosel bore rim 126. In step 4, the toe weight can be secured with the use of a screw.

The method of manufacturing a club head 100 with a hot melt weight 3000 can comprise (1) forming a hot melt weight with a first material (2) securing a cap 3050 to the shaft bottom end 144 (3) curing the hot melt weight 3000 (4) forming a ferrule 2000 using a second material (5) inserting the shaft 140 into the ferrule 2000 (6) securing the shaft 140 and ferrule 2000 into the hosel 122 (7) blending the ferrule 2000 (8) installing a toe weight. In step 1, the hot melt weight 3000 can be formed near a shaft bottom end 144. The first material, or the hot melt solution, can comprise a metal and a filler material. In some embodiments, the filler material can comprise Tungsten powder. In step 2, the cap 3050 can comprise a centering cap, or Christmas tree plug that can be press fit into the shaft bottom end 144. The cap 3050 can prevent any hot melt solution from leaking from the shaft 140. In step 3, the golf club can be positioned in a curing carousel such that the hot melt weight 3000 can rest near the shaft bottom end 144. In step 4, the ferrule 2000, can be injection molded. In some embodiments, the second material can comprise a resin. In other embodiments, the second material can comprise a resin mixture including a combination of a resin and a filler material. In some embodiments, the resin can comprise Cellulosic Acetate Propionate (CAP) resin, and the filler material can be steel or tungsten. In step 6, the shaft 140 can be secured within the hosel 122 with the use of an epoxy. A plurality of ribs 2044, located on the ferrule 2000, help center the shaft 140 within the hosel 122 by applying circumferential pressure to the hosel bore 124. A plurality of windows 2042, located on the ferrule 2000, allow excess epoxy to flow around the ferrule 2000 to increase bond strength between the shaft 140 and the hosel 122. In step 7, the ferrule 2000 can be blended with acetone to ensure the ferrule 2000 can be flush with the hosel bore rim 126. In step 8, the toe weight can be secured with the use of a screw.

EXAMPLES A. Example A: Microgroove Pull Test

A pull test was conducted to demonstrate the effect of microgrooves on epoxy tensile strength. The pull test measured the normal force required for the head-shaft connection to fail using different shafts. Each shaft was formed either with or without microgrooves, and the shaft insertion depths were varied. In each of the sample shafts, the effective bonding depth was equal to the shaft insertion depth. The purpose of the pull test was to determine how much additional strength was provided by adding microgrooves and increasing the shaft insertion depth.

The first sample shaft was a control shaft with no microgrooves and a 1.1 inch shaft insertion depth. The control shaft tip was prepared using the sanding method that is currently used to manufacture shafts. The second shaft was the first exemplary shaft having microgrooves similar to the microgrooves shown in FIGS. 3A and 3B. The first exemplary shaft had a 1.1 inch shaft insertion depth. The third shaft was the second exemplary shaft also having microgrooves similar to the microgrooves shown in FIGS. 3A and 3B. The second exemplary shaft had a 1.3 inch FSD and microgrooves. The microgrooves on the first and second exemplary shafts were similar, but the shaft insertion depths were altered. The microgrooves comprised a first and second plurality of interconnected microgrooves that were applied the entire shaft bonding area.

The pull test was conducted by securing the club and pulling the shaft away from the club head. Each of the three sample shafts was tested five times, and each test concluded when the epoxy bond failed explosively (demonstrating failure if a club head were to fly off). The pull test measured the force at which the connection fails at a certain displacement. This force translates to the strength of the head-shaft connection. The test measured the average strength over each of the five pull tests as well as the minimum strength for each sample shaft. For each test, the same amount of epoxy was used for each sample shaft, and the microgroove depth and pattern were held constant for the exemplary shafts.

TABLE 1 Pull Test Results Average Minimum Increase Increase Standard Tensile Tensile from Control from Control Deviation Sample Strength Strength (Average) (Minimum) (Average) Control 2756.77 2589.37 — — 151.14 Shaft First 3269.15 3153.92 18.59% 21.80% 102.27 Exemplary Shaft Second 3470.13 3292.90 25.88% 27.17% 174.21 Exemplary Shaft

The results of the pull test are shown in Table 1 above. The pull test concluded that shafts having microgrooves had a higher epoxy tensile strength. The average epoxy tensile strength of the control shaft was 2756.77 lbf with a standard deviation of 151.14 lbf. The minimum epoxy tensile strength of the control shaft was 2589.37 lbf.

The average epoxy tensile strength of the first exemplary shaft was 3269.15 lbf with a standard deviation of 102.27 lbf. The average epoxy tensile strength of the first exemplary shaft increased from the control shaft by 18.59% (512.38 lbf). The minimum epoxy tensile strength of the first exemplary shaft was 3153.92 lbf, a 21.80% increase from the control shaft. The control shaft and the first exemplary shaft had the same shaft insertion depth, but the first exemplary shaft had a larger effective bonding area due to the presence of microgrooves. The first exemplary shaft demonstrated the added strength of the shaft when the shaft insertion depth was held constant, and microgrooves were added.

The average epoxy tensile strength of the second exemplary shaft was 3470.13 lbf with a standard deviation of 174.21 lbf. The average epoxy tensile strength of the second exemplary shaft increased from the control test by 25.88% (713.36 lbf). The minimum epoxy tensile strength of the second exemplary shaft was 3292.90 lbf, a 27.17% increase. The second exemplary shaft had a deeper shaft insertion depth than both the control shaft and the first exemplary shaft. By increasing the shaft insertion depth from 1.1 inch to 1.3 inch, the average epoxy tensile strength of the second exemplary shaft increased by 200.98 lbf compared to the first exemplary shaft. The second exemplary shaft demonstrated the added strength of the shaft when the shaft insertion depth was increased. The pull test concluded that introducing microgrooves to the shaft and increasing the shaft insertion depth significantly increased the bond strength between the club head and the shaft.

B. Example B: Microgroove Pull Test (Hosel Microgroove Comparison)

A pull test, similar to the pull test in example A, was conducted to demonstrate the effect of the depth of the microgrooves as well compare the bonding strength of microgrooves located on the hosel versus microgrooves located on the shaft. The pull test determines the max force the club head/shaft connection can withstand before failing. A higher force indicates a stronger connection. The pull test compared two exemplary club heads according to an embodiment and a control club head.

The control club head comprised a club head body, a hosel, and a shaft. The shaft did not have microgrooves. The hosel comprised microgrooves within the internal surface of the hosel bore. The grooves extended in a perpendicular direction to the longitudinal axis 110. The grooves were parallel and equally spaced apart such that they did not intersect. Furthermore, the grooves had a depth of 0.003″. The depth of the grooves did not sacrifice the shaft durability.

The first exemplary club head had a shaft with horizontal microgrooves, as illustrated in FIG. 4. The shaft had four microgrooves that were equally spaced apart and parallel such that they were not intersecting. The microgrooves had a depth of 0.002″.

The second sample had a shaft with horizontal microgrooves, similar to the first sample and as illustrated in FIG. 4. The shaft had four microgrooves that were equally spaced apart and parallel such that they were not intersecting. The microgrooves had a depth of 0.006″.

TABLE 3 Microgroove Pull Test Results Bond Strength Increase from Control Test Sample (lbf) Club Head (lbf) Control Club Head 2034.98 — First Exemplary Club Head 2198.60 163.62 Second Exemplary Club head 2308.91 273.93

The results of the pull test are shown in Table 3 above. The pull test concluded that a club head having microgrooves on the shaft had a higher bonding strength than a club head having microgrooves on the hosel. Furthermore, the test concluded that deeper microgrooves had a higher bonding strength than shallower microgrooves.

The first exemplary club head had a bonding strength of 2198.60 lbf and an increase of 163.62 lbf (8%) over the control club head. Therefore, shafts having microgrooves have better bonding strength than hosels having microgrooves.

The second exemplary club head had a bonding strength of 2308.91 lbf and an increase of 273.93 lbf (13.4%) over the control club head. Furthermore, the second exemplary club head had an increase of 110.31 lbf over the first exemplary club head. Increasing the groove depth from 0.002″ to 0.006″ increased the bonding strength.

C. Example C: Ferrule Extreme Temperature Test

An extreme temperature (ET) test was performed to assess the durability of several ferrules comprising different weighting elements under extreme temperature controlled conditions. The purpose of this test is to determine how several weighted ferrule designs perform under stress at a wide range of temperatures. In other words, the ET test demonstrated the flexibility and resistance to fracture of the weighted ferrule designs.

Three different weighted ferrule designs were tested on assembled golf clubs. Each of the three ET tests assessed one of the ferrule designs and used between four to five sample golf clubs, each having the same ferrule design. Each sample golf club was assembled using the respective weighted ferrule and cured for 24 hours prior to the test. Each sample was placed in a freezer at approximately 0° F. for approximately 2 hours. The temperature of the sample was taken upon removal from the freezer. The sample was then used to hit 30 “cold” hits near a low-toe area of the club face. The temperature of each sample was then taken after the 30 cold hits. The sample was then placed into an oven at approximately 200° F. for approximately 2 hours. The temperature of the test sample was taken upon removal from the oven. Again, the sample is then used to hit 30 “hot” hits near a low-toe area of the club face. The temperature of each sample was then taken after the 30 hot hits. Each sample is determined to either pass or fail the ET test. A failing sample shows signs of wear such as cracks, fracturing, chipping, or twisting. In contrast, a passing sample does not show signs of wear.

Each sample was an iron-type golf club. Throughout the three tests, the material of the weighted ferrule was held constant. Each sample included a ferrule formed from a CAP resin used to form a traditional ferrule. Each sample further included an internal weight formed from steel. The three tests assess ferrules having internal weights with different masses and dimensions. The dimensions of the internal weight such as the outer diameter and the height were adjusted throughout the tests to balance the mass and volume of the internal weight material with the ferrule body material. The balance in materials affects the strength and flexibility of the ferrule. Another critical dimension is the curvature of the internal weight edges. The internal weight includes an upper and lower edge each having a curvature. The curvature was adjusted throughout the tests to decrease stress points throughout the ferrule.

First Test: The first ET test used five test samples. The mass of the internal weight was 3.69 grams, and the mass of the assembled ferrule was 4.54 grams. The curvature of the edges was 0.1 inch. The results of the first ET are illustrated in Table 1 below. Each of the samples passed the first 30 shots but failed on the second 30 shots. The first test resulted in a 0% success rate.

TABLE 1 Results of First ET Test Cold Cold Hot Hot Result Result Test Start End Start End After After Sample (° F.) (° F.) (° F.) (° F.) Cold Hits Hot Hits 1 11.0 64.0 182.4 93.2 Pass Fail 2 10.6 64.2 180.0 92.8 Pass Fail 3 11.2 64.4 179.8 93.4 Pass Fail 4 6.8 62.8 181.4 94.0 Pass Fail 5 6.6 62.2 179.6 91.8 Pass Fail

Second Test: The second ET test again used 5 test samples. The mass of the internal weight was 3.80 grams, and the mass of the assembled ferrule was 4.60 grams. The height of the internal weight was 0.65 inch, and the outer diameter was 0.490 inch. The internal weight used in the second test included more rounded corners (a larger curvature). The corners can provide stress points and removing them can prevent cracking. The curvature was changed from 0.1 inch to 0.4 inch. The results of the second ET are illustrated in Table 2 below. In the second test, only 2 of the samples failed while 3 of the 5 samples passed. The second test resulted in a 60% pass rate.

TABLE 2 Results of Second ET Test Cold Cold Hot Hot Result Result Test Start End Start End After After Sample (° F.) (° F.) (° F.) (° F.) Cold Hits Hot Hits 1 7.4 63.6 180.0 90.6 Pass Pass 2 7.2 63.6 179.8 89.0 Pass Fail 3 6.4 63.4 178.8 89.4 Pass Fail 4 7.2 63.8 179.2 90.8 Pass Pass 5 7.8 63.8 181.2 91.6 Pass Pass

Third Test: The third ET test used 4 samples. The mass of the internal weight was X grams, and the mass of the assembled ferrule was X grams. In comparison to the second test samples, the outer diameter of the internal weight was reduced from 0.490 inch to 0.436 inch, and the length was reduced from 0.65 inch to 0.63 inch. The outer diameter was decreased in comparison to the second test, but still larger than that of the ferrule in the first test. The third test again used ferrules with more rounded corners that the samples used in the first test. The curvature was reduced from 0.4 inch to 0.3 inch. The results of the third ET are illustrated in Table 3 below. In the third ET test, all four of the samples passed. The third test resulted in a 100% pass rate.

TABLE 3 Results of Third ET Test Cold Cold Hot Hot Result Result Test Start End Start End After After Sample (° F.) (° F.) (° F.) (° F.) Cold Hits Hot Hits 1 8.0 69.8 181.4 93.6 Pass Pass 2 9.2 70.0 181.2 93.8 Pass Pass 3 9.0 70.2 180.6 91.8 Pass Pass 4 9.8 70.4 181.0 94.8 Pass Pass

The results of the three tests illustrate the effects of internal weight dimensions on durability. The results show that decreasing the weights height and diameter will improve durability of the ferrule. Further, increasing the curvature of the rounded corners will improve durability of the ferrule. The geometry of the weight and ferrule used in test 3 showed 100% pass rate. Therefore, the weighted ferrule design is durable and can be successfully implemented into a product without failure.

D. Example D: Weighted Ferrule Mass Properties Example

A comparative test was conducted between an exemplary club head comprising a weighted ferrule, and a control club head comprising a ferrule and a tip weight. The test was done to compare the center of gravity location and the moment of inertia properties. The center of gravity and moment of inertia properties are defined within the coordinate system and center of gravity coordinate system described above. The test used computer aided design software to determine the location of the center of gravity and the moment of inertia.

The exemplary club head comprised a club head, a shaft, and a weighted ferrule, similar to the embodiment illustrated in FIGS. 12A and 12B. The weighted ferrule had a total weight of 7.35 grams. The exemplary club head did not have a tip weight such that the shaft was inserted further into the hosel to improve the bonding strength.

The control club head comprised the same club head geometries as the exemplary club head. The control club head further comprised a ferrule with a mass of 1.35 grams. The ferrule of the control club head did not have weighting elements. The control club head further comprised a 6 gram tip weight such that the shaft insertion depth was less than that of the exemplary embodiment described above.

TABLE 4 Results of Mass Properties Test Ferrule Tip Weight Sample (g) (g) CGx CGy Ixx Iyy Exemplary Club 7.35 0 0.065 0.631 139.7 545.6 Head Control Club Head 1.35 6 0.048 0.598 118.6 523

The exemplary club head comprised a CG location along the x-axis. The CGx was 0.065 inch. The exemplary club head further comprised a CG location along the y-axis. The CGy was 0.631 inch. The exemplary club head further comprised a MOI about the x-axis. The Ixx was 139.7. The exemplary club head further comprised a MOI about the y-axis. The Iyy was 545.6.

The control club head comprised a CG location along the x-axis. The CGx was 0.048 inch. The control club head comprised a CG location along the y-axis. The CGy was 0.598 inch. The control club head comprised a MOI about the x-axis. The Ixx was 118.6. The control club head comprised a MOI about the y-axis. The Iyy was 523.

The exemplary club head a CGx location that was 0.017 inch further along the x-axis (heelward) than the control club head. Furthermore, the exemplary club head had a CGy location that was 0.033 inch further along the y-axis (upwards) than the control club head. The exemplary club head had a 17.8% increase in Ixx over the control club head. The exemplary club head had a 4.3% increase in Iyy over the control club head.

Therefore, the exemplary club head comprising a weighted ferrule had an increase in moment of inertia about both the x-axis and y-axis when compared to a control club head comprising a tip weight. The increase in moment of inertia will provide the exemplary club head with an improvement in performance over the control club head. Furthermore, the weighted ferrule further has improved bonding strength because the shaft is inserted further into the hosel than the control club head comprising a tip weight.

Clauses

Clause 1: A golf club comprising: a club head, a shaft, and a grip, wherein: the club head comprises a body and a hosel, wherein: the hosel comprises a hosel bore having an inner surface that defines a hosel bonding area; the shaft comprises a shaft tip end, a shaft butt end, and a shaft outer surface, wherein: the hosel bore receives the shaft tip end forming a head-shaft connection; the shaft defines a longitudinal axis that runs from a geometric center of the shaft butt end to a geometric center of the shaft tip end; the shaft outer surface defines a shaft bonding area, and an effective bonding area near the shaft tip end, wherein the shaft bonding area is a portion of the shaft outer surface that is inserted into the hosel bore, and the effective bonding area is a portion of the shaft outer surface that is in contact with the hosel bonding area; the effective bonding area comprises a plurality of microgrooves, wherein: the plurality of microgrooves are recessed into the shaft away from the shaft outer surface via a plurality of side walls, and the plurality of side walls increase the effective bonding area; the plurality of microgrooves are formed in lines and define a first plurality of microgrooves, extending in a first direction, and a second plurality of microgrooves, extending in a second direction; the first plurality of microgrooves, and the second plurality of microgrooves are interconnected and extend circumferentially around the shaft; and the grip is coupled to the shaft butt end.

Clause 2: The golf club of clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves are formed integrally with the shaft.

Clause 3: The golf club of clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves define an individual microgroove depth; wherein the individual microgroove depth is less than 0.0038 inch.

Clause 4: The golf club of clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves define a total microgroove depth, wherein: the total microgroove depth is measured along the longitudinal axis, and the total microgroove depth is a depth of the shaft tip end that comprises microgrooves, and the total microgroove depth is between 1.00 inch to 3.00 inches.

Clause 5: The golf club of clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves cover between 50% to 90% of the shaft bonding area.

Clause 6: The golf club of clause 1, wherein the plurality of microgrooves each comprise a floor, wherein the floor is perpendicular to the plurality of side walls of an individual microgroove, and the individual microgroove is U-shaped in a cross-sectional view.

Clause 7: The golf club of clause 1, wherein each microgroove of the first plurality of microgrooves extends in the first direction and is parallel to the adjacent microgrooves of the first plurality of microgrooves, and each microgroove of the second plurality of microgrooves extends in the second direction and is parallel to the adjacent microgrooves of the second plurality of microgrooves.

Clause 8: The golf club of clause 7, wherein the first direction and the second direction are diagonal relative to the longitudinal axis.

Clause 9: The golf club of clause 8, wherein the first plurality of microgrooves and the second plurality of microgrooves provide resistance to a normal force and a torsional force.

Clause 10: The golf club of clause 7, wherein the first direction is perpendicular to the longitudinal axis, and the second direction is parallel to the longitudinal axis.

Clause 11: A golf club comprising: a club head, a shaft, and a grip, wherein: the club head comprises a body and a hosel, wherein: the hosel comprises a hosel bore having an inner surface that defines a hosel bonding area; the shaft comprises a shaft tip end, a shaft butt end, and a shaft outer surface, wherein: the hosel bore receives the shaft tip end forming a head-shaft connection; the shaft defines a longitudinal axis that runs from a geometric center of the shaft butt end to a geometric center of the shaft tip end; the shaft outer surface defines a shaft bonding area, and an effective bonding area near the shaft tip end, wherein the shaft bonding area is a portion of the shaft outer surface that is inserted into the hosel bore, and the effective bonding area is a portion of the shaft outer surface that is in contact with the hosel bonding area; the effective bonding area comprises a plurality of microgrooves, wherein: the plurality of microgrooves are recessed into the shaft away from the shaft outer surface via a plurality of side walls, and the plurality of side walls increase the effective bonding area; the plurality of microgrooves are formed in shapes; the plurality of microgrooves are not interconnected and extend circumferentially around the shaft; and the grip is coupled to the shaft butt end.

Clause 12: The golf club of clause 11, wherein the plurality of microgrooves are formed integrally with the shaft.

Clause 13: The golf club of clause 11, wherein the plurality of microgrooves define an individual microgroove depth; wherein the individual microgroove depth is less than 0.0038 inch.

Clause 14: The golf club of clause 11, wherein the plurality of microgrooves define a total microgroove depth, wherein: the total microgroove depth is measured along the longitudinal axis, and the total microgroove depth is a depth of the shaft tip end that comprises microgrooves, and the total microgroove depth is between 1.00 inch to 3.00 inches.

Clause 15: The golf club of clause 11, wherein the plurality of microgrooves cover between 50% to 90% of the shaft bonding area.

Clause 16: The golf club of clause 11, wherein the plurality of microgrooves each comprise a floor, wherein the floor is perpendicular to the plurality of side walls of an individual microgroove, and the individual microgroove is U-shaped in a cross-sectional view.

Clause 17: The golf club of clause 11, wherein each microgroove comprises a shape selected from a group consisting of: triangles, lines, squares, rectangles, or spirals.

Clause 18: The golf club of clause 17, wherein each of the microgrooves comprises the same shape.

Clause 19: The golf club of clause 17, wherein each of the microgrooves comprises a different shape.

Clause 20: The golf club of clause 11, wherein the plurality of microgrooves provide resistance to a normal force and a torsional force.

Clause 21: A golf club comprising: a club head, a shaft, a grip, and a ferrule: wherein the club head comprises a body and a hosel comprising a hosel rim, a hosel base, and a hosel inner surface, wherein: the hosel inner surface defines a hosel bore that extends from the hosel rim to the hosel base; the shaft comprises a top end received within the grip, a bottom end received within the hosel bore, and a diameter; the ferrule comprises a top edge, a bottom edge, a ledge, an exterior surface, and interior surface, a centering region, and a tapered region, wherein: the ledge defines a boundary between the tapered region and the centering region; the centering region is a lower portion of the ferrule defined between the ledge and the bottom edge, and the centering region is received within the hosel bore; the tapered region is an upper portion of the ferrule defined between the ledge and the top edge, and the tapered region comprises an internal weight, wherein: the internal weight comprises a cylindrical tube having a top perimeter, a bottom perimeter, an inner surface, an outer surface, and a gap.

Clause 22: The golf club of clause 21, wherein the internal weight is formed integrally with the tapered region.

Clause 23: The golf club of clause 21, wherein the inner surface of the internal weight forms a portion of the interior surface of the ferrule.

Clause 24: The golf club of clause 21, wherein the gap defines an opening extending from the top perimeter to the bottom perimeter.

Clause 25: The golf club of clause 24, wherein the gap comprises a gap width between 0.01 inch to 0.5 inch.

Clause 26: The golf club of clause 21, wherein the internal weight comprises a height between 0.5 inch to 0.7 inch.

Clause 27: The golf club of clause 21, wherein the internal weight comprises a thickness between 0.01 inch to 0.09 inch.

Clause 28: The golf club of clause 27, wherein the thickness of the internal weight increases from the top perimeter to the bottom perimeter.

Clause 29: The golf club of clause 21, wherein the centering region comprises a plurality of windows to increase epoxy flow around the shaft to create a stronger bond between the shaft and the hosel.

Clause 30: The golf club of clause 21, wherein the centering region further comprises a plurality of ribs; wherein the plurality of ribs are equally spaced throughout the centering region; and wherein the plurality of ribs apply equal pressure against the hosel bore to center the shaft within the hosel.

Clause 31: A golf club comprising: a club head, a shaft, a grip, and a ferrule: wherein the club head comprises a body and a hosel comprising a hosel rim, a hosel base, and a hosel inner surface, wherein the hosel inner surface defines a hosel bore that extends from the hosel rim to the hosel base; the shaft comprises a top end received within the grip, a bottom end received within the hosel bore, and a diameter; the ferrule comprises a top edge, a bottom edge, a ledge, a centering region, and a tapered region, wherein: the ledge defines a boundary between the tapered region and the centering region; the centering region is a lower portion of the ferrule defined between the ledge and the bottom edge, and the centering region is received within the hosel bore; the tapered region is an upper portion of the ferrule defined between the ledge and the top edge, and the tapered region comprises one or more weighted rings, wherein: the one or more weighted rings each comprise a cylindrical tube having a top perimeter, a bottom perimeter, an inner surface, an outer surface.

Clause 31: The golf club of clause 31, wherein the one or more weighted rings are formed integrally with the tapered region.

Clause 32: The golf club of clause 31, wherein the outer surface of each of the one or more weighted rings forms a portion of the exterior surface of the ferrule.

Clause 33: The golf club of clause 31, wherein the one or more weighted rings can be one ring, two rings, three rings, four rings, or five rings.

Clause 34: The golf club of clause 31, wherein the one or more weighted rings comprise a height between 0.1 inch and 0.5 inch.

Clause 35: The golf club of clause 35, wherein the height of each of the one or more weighted rings is the same.

Clause 36: The golf club of clause 35, wherein the height of each of the one or more weighted rings is different.

Clause 37: The golf club of clause 31, wherein the one or more weighted rings comprise a thickness between 0.01 inch to 0.08 inch.

Clause 38: The golf club of clause 31, wherein the one or more weighted rings are formed from a metallic material selected from the group consisting of: Stainless Steel, Tungsten, a Tungsten-Tenite Propionate mixture, or a Stainless Steel-Tenite Propionate mixture.

Clause 39: The golf club of clause 31, wherein the one or more weighted rings comprise a combined mass between 1 gram to 10 grams.

Clause 40: A golf club comprising a club head, a shaft, and a grip: wherein the club head comprises a body and a hosel having a bore; wherein the shaft comprises a top end, a bottom end, a hot melt weight and a cap; wherein the top end is near the grip, the bottom end is opposite the top end, near the club head, and the bottom end is received within the hosel; and wherein the hot melt weight is formed inside of the shaft near the bottom end and the cap is secured at the bottom end.

Replacement of one or more claimed elements constitutes reconstruction and not repair. Additionally, benefits, other advantages, and solutions to problems have been described with regard to specific embodiments. The benefits, advantages, solutions to problems, and any element or elements that may cause any benefit, advantage, or solution to occur or become more pronounced, however, are not to be construed as critical, required, or essential features or elements of any or all of the claims, unless such benefits, advantages, solutions, or elements are stated in such claim.

Moreover, embodiments and limitations disclosed herein are not dedicated to the public under the doctrine of dedication if the embodiments and/or limitations: (1) are not expressly claimed in the claims; and (2) are or are potentially equivalents of express elements and/or limitations in the claims under the doctrine of equivalents. 

1. A golf club comprising: a club head, a shaft, and a grip, wherein: the club head comprises a body and a hosel, wherein: the hosel comprises a hosel bore having an inner surface that defines a hosel bonding area; the shaft comprises a shaft tip end, a shaft butt end, and a shaft outer surface, wherein: the hosel bore receives the shaft tip end forming a head-shaft connection; the shaft defines a longitudinal axis that runs from a geometric center of the shaft butt end to a geometric center of the shaft tip end; the shaft outer surface defines a shaft bonding area, and an effective bonding area near the shaft tip end, wherein the shaft bonding area is a portion of the shaft outer surface that is inserted into the hosel bore, and the effective bonding area is a portion of the shaft outer surface that is in contact with the hosel bonding area; the effective bonding area comprises a plurality of microgrooves, wherein: the plurality of microgrooves are recessed into the shaft away from the shaft outer surface via a plurality of side walls, and the plurality of side walls increase the effective bonding area; the plurality of microgrooves are formed in lines and define a first plurality of microgrooves, extending in a first direction, and a second plurality of microgrooves, extending in a second direction; the first plurality of microgrooves, and the second plurality of microgrooves are interconnected and extend circumferentially around the shaft; and the grip is coupled to the shaft butt end.
 2. The golf club of claim 1, wherein the first plurality of microgrooves and the second plurality of microgrooves are formed integrally with the shaft.
 3. The golf club of claim 1, wherein the first plurality of microgrooves and the second plurality of microgrooves define an individual microgroove depth; wherein the individual microgroove depth is less than 0.0038 inch.
 4. The golf club of claim 1, wherein the first plurality of microgrooves and the second plurality of microgrooves define a total microgroove depth, wherein: the total microgroove depth is measured along the longitudinal axis, and the total microgroove depth is a depth of the shaft tip end that comprises microgrooves, and the total microgroove depth is between 1.00 inch to 3.00 inches.
 5. The golf club of claim 1, wherein the first plurality of microgrooves and the second plurality of microgrooves cover between 50% to 90% of the shaft bonding area.
 6. The golf club of claim 1, wherein the plurality of microgrooves each comprise a floor, wherein the floor is perpendicular to the plurality of side walls of an individual microgroove, and the individual microgroove is U-shaped in a cross-sectional view.
 7. The golf club of claim 1, wherein each microgroove of the first plurality of microgrooves extends in the first direction and is parallel to the adjacent microgrooves of the first plurality of microgrooves, and each microgroove of the second plurality of microgrooves extends in the second direction and is parallel to the adjacent microgrooves of the second plurality of microgrooves.
 8. The golf club of claim 7, wherein the first direction and the second direction are diagonal relative to the longitudinal axis.
 9. The golf club of claim 8, wherein the first plurality of microgrooves and the second plurality of microgrooves provide resistance to a normal force and a torsional force.
 10. The golf club of claim 7, wherein the first direction is perpendicular to the longitudinal axis, and the second direction is parallel to the longitudinal axis.
 11. A golf club comprising: a club head, a shaft, and a grip, wherein: the club head comprises a body and a hosel, wherein: the hosel comprises a hosel bore having an inner surface that defines a hosel bonding area; the shaft comprises a shaft tip end, a shaft butt end, and a shaft outer surface, wherein: the hosel bore receives the shaft tip end forming a head-shaft connection; the shaft defines a longitudinal axis that runs from a geometric center of the shaft butt end to a geometric center of the shaft tip end; the shaft outer surface defines a shaft bonding area, and an effective bonding area near the shaft tip end, wherein the shaft bonding area is a portion of the shaft outer surface that is inserted into the hosel bore, and the effective bonding area is a portion of the shaft outer surface that is in contact with the hosel bonding area; the effective bonding area comprises a plurality of microgrooves, wherein: the plurality of microgrooves are recessed into the shaft away from the shaft outer surface via a plurality of side walls, and the plurality of side walls increase the effective bonding area; the plurality of microgrooves are formed in shapes; the plurality of microgrooves are not interconnected and extend circumferentially around the shaft; and the grip is coupled to the shaft butt end.
 12. The golf club of claim 11, wherein the plurality of microgrooves are formed integrally with the shaft.
 13. The golf club of claim 11, wherein the plurality of microgrooves define an individual microgroove depth; wherein the individual microgroove depth is less than 0.0038 inch.
 14. The golf club of claim 11, wherein the plurality of microgrooves define a total microgroove depth, wherein: the total microgroove depth is measured along the longitudinal axis, and the total microgroove depth is a depth of the shaft tip end that comprises microgrooves, and the total microgroove depth is between 1.00 inch to 3.00 inches.
 15. The golf club of claim 11, wherein the plurality of microgrooves cover between 50% to 90% of the shaft bonding area.
 16. The golf club of claim 11, wherein the plurality of microgrooves each comprise a floor, wherein the floor is perpendicular to the plurality of side walls of an individual microgroove, and the individual microgroove is U-shaped in a cross-sectional view.
 17. The golf club of claim 11, wherein each microgroove comprises a shape selected from a group consisting of: triangles, lines, squares, rectangles, or spirals.
 18. The golf club of claim 17, wherein each of the microgrooves comprises the same shape.
 19. The golf club of claim 17, wherein each of the microgrooves comprises a different shape.
 20. The golf club of claim 11, wherein the plurality of microgrooves provide resistance to a normal force and a torsional force. 